This article explores the following questions: What environmental and cultural factors might explain variation in prejudice across cultures? Do these factors explain the intention to vote for nationalist politicians? The authors perform seven studies, focusing on the link between cultural tightness and the rise of prejudice in cultures. They theorize that cultural tightness is positively correlated with the rise of prejudice against people perceived as disrupting the social order. From this theory, they suggest three hypotheses: 1) cultural variation in tightness is related to cultural variation in prejudice, 2) cultural tightness is related to the support for nationalist politicians, and 3) cultural tightness is a link between ecological threats and prejudice. The results support these hypotheses, offering a cultural evolutionary perspective on prejudice.

Drawing from previous theories on the cultural variation of depression, this article tested the relationship between 24 sociocultural and ecological factors and the prevalence of depression across 195 countries and territories. The authors first conducted a zero-order association test to find the most contributory factors. Those variables were further tested in a regression model, and controlled for the under-reporting of depression by measuring the number of healthcare workers per capita. The authors found that cultural individualism was the only factor that positively predicted depression prevalence in a multiple regression model.

This article examines the relationship between the tightness-looseness of a culture and the variation of COVID-19 cases and deaths through October 2020. With COVID-19 data retrieved from Our World in Data from 57 countries with tightness-looseness figures, the article found the cultures with high levels of tightness had fewer COVID-19 cases and deaths when compared to countries with high levels of looseness. Results suggest support of the evolutionary game theoretic model proposing that people in tight cultures may cooperate with more urgency when under collective threat than people in loose cultures.